package com.oceansoft.mobile.econsole.modules.api.util;

import java.security.Key;

import javax.crypto.Cipher;

/**
 * 加密、解密辅助类
 * <p>
 * 说明：
 * </p>
 * <p>
 * 1、DES加、解密时的Key已经内置, 这样做的好处有两点:A. 避免维护服务器与手机端Key的同步;B.给客户的调用提供便利;
 * </p>
 * <p>
 * 2、为了避免在数据传输的过程中产生乱码, 只对外提供了String类型数据的加、解密;
 * </p>
 *
 * @author seventh7
 */
public class SimpleDesGA {
    public static final String UTF8 = "UTF-8";
    public static final String GBK = "GBK";

    public static String strDefaultKey = "szgakeys";
    public String charset = UTF8;
    public Cipher encryptCipher = null;
    public Cipher decryptCipher = null;

    /**
     * 将byte数组转换为表示16进制值的字符串， 如：byte[]{8,18}转换为：0813， 和public static byte[]
     * hexStr2ByteArr(String strIn) 互为可逆的转换过程
     *
     * @param bytes 需要转换的byte数组
     * @return 转换后的字符串
     * @throws Exception 本方法不处理任何异常，所有异常全部抛出
     */
    public static String byteArr2HexStr(byte[] bytes) throws Exception {
        int iLen = bytes.length;
        // 每个byte用两个字符才能表示，所以字符串的长度是数组长度的两倍
        StringBuffer sb = new StringBuffer(iLen * 2);
        for (int i = 0; i < iLen; i++) {
            int intTmp = bytes[i];
            // 把负数转换为正数
            while (intTmp < 0) {
                intTmp = intTmp + 256;
            }
            // 小于0F的数需要在前面补0
            if (intTmp < 16) {
                sb.append("0");
            }
            sb.append(Integer.toString(intTmp, 16));
        }
        return sb.toString();
    }

    /**
     * 将表示16进制值的字符串转换为byte数组， 和public static String byteArr2HexStr(byte[] arrB)
     * 互为可逆的转换过程
     *
     * @param text 需要转换的字符串
     * @return 转换后的byte数组
     * @throws Exception 本方法不处理任何异常，所有异常全部抛出
     * @author
     */
    public byte[] hexStr2ByteArr(String text) throws Exception {
        byte[] arrB = text.getBytes(charset);
        int iLen = arrB.length;

        // 两个字符表示一个字节，所以字节数组长度是字符串长度除以2
        byte[] arrOut = new byte[iLen / 2];
        for (int i = 0; i < iLen; i = i + 2) {
            String strTmp = new String(arrB, i, 2);
            arrOut[i / 2] = (byte) Integer.parseInt(strTmp, 16);
        }
        return arrOut;
    }

    /**
     * 默认构造方法，使用默认密钥
     *
     * @throws Exception
     */
    public SimpleDesGA() throws Exception {
        this(strDefaultKey);
    }

    /**
     * 指定密钥构造方法
     *
     * @param key 指定的密钥
     * @throws Exception
     */
    public SimpleDesGA(String key) throws Exception {
        Key keyTmp = getKey(key.getBytes(charset));

        encryptCipher = Cipher.getInstance("DES");
        encryptCipher.init(Cipher.ENCRYPT_MODE, keyTmp);

        decryptCipher = Cipher.getInstance("DES");
        decryptCipher.init(Cipher.DECRYPT_MODE, keyTmp);
    }

    /**
     * 加密字节数组
     *
     * @param bytes 需加密的字节数组
     * @return 加密后的字节数组
     * @throws Exception
     */
    public byte[] encrypt(byte[] bytes) throws Exception {
        return encryptCipher.doFinal(bytes);
    }

    /**
     * 解密字节数组
     *
     * @param bytes 需解密的字节数组
     * @return 解密后的字节数组
     * @throws Exception
     */
    public byte[] decrypt(byte[] bytes) throws Exception {
        return decryptCipher.doFinal(bytes);
    }

    /**
     * 加密字符串
     *
     * @param text 需加密的字符串(明文)
     * @return 加密后的字符串(密文)
     * @throws Exception 加密时, direction的值只能是DataDirection.TO_MOBILE 或
     *                   DataDirection.TO_SERVER, 否则会抛出LawlessDataDirectionException
     */
    public static String encrypt(String text, DataDirection direction)
            throws Exception {
        if (direction == DataDirection.FROM_MOBILE
                || direction == DataDirection.FROM_SERVER)
            throw new LawlessDataDirectionException(
                    "direction can't be FROM_MOBILE or FROM_SERVER when encrypt!!");
        if (text == null) {
            text = "";
        }
        // return byteArr2HexStr(encrypt(strIn.getBytes()));
        SimpleDesGA des = new SimpleDesGA();
        if (direction == DataDirection.TO_MOBILE) {
            des.setCharset(SimpleDesGA.UTF8);
        } else if (direction == DataDirection.TO_SERVER) {
            des.setCharset(SimpleDesGA.UTF8);
        }

        return SimpleDesGA.byteArr2HexStr(des.encrypt(text.getBytes(des.getCharset())));
    }

    /**
     * 解密字符串
     *
     * @param text 需解密的字符串(密文)
     * @return 解密后的字符串(明文)
     * @throws Exception 解密时, direction的值只能是DataDirection.FROM_MOBILE 或
     *                   DataDirection.FROM_SERVER, 否则会抛出LawlessDataDirectionException
     */
    public static String decrypt(String text, DataDirection direction)
            throws Exception {
        if (direction == DataDirection.TO_MOBILE
                || direction == DataDirection.TO_SERVER)
            throw new LawlessDataDirectionException(
                    "direction can't be TO_MOBILE or TO_SERVER when decrypt!!");
        // return new String(decrypt(hexStr2ByteArr(strIn)));
        SimpleDesGA des = new SimpleDesGA();
        if (direction == DataDirection.FROM_MOBILE) {
            des.setCharset(SimpleDesGA.UTF8);
        } else if (direction == DataDirection.FROM_SERVER) {
            des.setCharset(SimpleDesGA.UTF8);
        }
        byte[] bytes = des.decrypt(des.hexStr2ByteArr(text));
        return new String(bytes);
    }

    /**
     * 从指定字符串生成密钥，密钥所需的字节数组长度为8位 不足8位时后面补0，超出8位只取前8位
     *
     * @param bytes 构成该字符串的字节数组
     * @return 生成的密钥
     * @throws Exception
     */
    public Key getKey(byte[] bytes) throws Exception {
        // 创建一个空的8位字节数组（默认值为0）
        byte[] arrB = new byte[8];

        // 将原始字节数组转换为8位
        for (int i = 0; i < bytes.length && i < arrB.length; i++) {
            arrB[i] = bytes[i];
        }

        // 生成密钥
        Key key = new javax.crypto.spec.SecretKeySpec(arrB, "DES");

        return key;
    }

    public static void main(String[] args) {
        String os = System.getProperty("os.name");
        if (os.toLowerCase().startsWith("win")) {
            System.out.println(os + " can't gunzip");
        }
    }

    public void setCharset(String charset) {
        this.charset = charset;
    }

    public String getCharset() {
        return charset;
    }

}